Cimorene

I was just going to mention this -- I have used a diaper shell that's easily washable and put either women's maxi pads in (these are especially great for belly bands), or a full adult diaper or pad.

I have a feeling it is age -- I've seen many very old dogs just walk along, pooping as they go, completely unaware that they're doing it. I hate to say this, but it's often and end-stage thing (though the end stage can last a long time).